Loss of crop yields due to the attack of various insects is a worldwide problem. Insect pests are of mainly of two different types; biting and chewing type (e.g. Lepidopteran insects) & piercing and sucking type (Hemipteran insects). Transgenic insect resistant cultivars expressing Bacillus thuringiensis (Bt) protein have been developed for the control of insect pests of order Lepidoptera and Coleoptera group. However, the plants expressing Bt protein are not toxic to sap sucking pests. Hence, an alternative approach is required to control sap sucking pests. One of the approaches would be screening of plant biodiversity for insect toxic proteins.